If he turns out to be the Red Skull, I think the image of what espionage has become still works. If Pierce is his own character, yes I'd prefer him to not be entirely wrong but corrupted. But, think of the symbolic image if he is indeed the Red Skull. The new world of espionage has become so murky, that one of the most notoriously evil men ever was able to rise through the ranks and eventually take it over. This is a world that has decayed so much that the power of evil men keeps growing. I think that image, especially for a Captain America movie, is strong and works extremely well.

That actually would be pretty interesting. But at the same time, I would like for Cap to have an enemy that isn't too easy for him to justify himself. Skull as the villain makes it too easy for him to reassure himself that he's doing the right thing. But a man who seems to truly want what he thinks is best, and may actually have solid points...that's harder, and not something we've seen Cap up against.

Now, what would be REALLY scary would be if we see that Skull has actually evolved into that kind of person. Who, while still wanting power, actually does have good points about what he thinks would be best for the world.

Also, I didn't put this in spoiler tags since it's just speculation, but if you want me to I can definitely do that.